Smelting furnace with coal-dust firing



Sept. 29, 1925.' H. LscHE l SMEL'VIING FURNACE WITH COAL DUST FIRINGFiled July 23, 2.1925 2 Sheets-Sheet l wif/fesses 1,555,423 H. LSCHE-SMELTING FURNACE WITH COAL DUST FIRING v Filed July 23. 1923 .2Sheets-Shoe?.v 2

I l l I I l l I "l 1 Il fnveno Sept. 29, 1925.

and useful Improvements in Smelting Fur-` Patented Sept. 29, 1925.

HANNS IiSCHE, 0F COLOGNE-MULEIM, GERMANY.

SMELTING FRNACE WITH COAL-DUST .FIING.

Application le. July 23, 1923. Serial No. 653,168.

To all whom t 'may come/m:

Be itknown that I, HANNs LSCHE, residing 'at Cologne-Mulheim, `State ofPrussia, Germany, have invented certain new naces with Coal-Dust Firing,of which the following is a specification. c

This invention relates to smelting furnaces and, more particularly, tofurnaces for smelting steel and iron of the open hearth type with whichcoal dust irings are used instead of the gas firings or partial gasfirings mostly in use with such furnaces.

The invention has for its primary object to` provide an open hearthfurnace of the kind stated with which the point of injection for thepowdered fuel is arranged, in the form of one or more injecting nozzles,in a perforation of the crown of lthe furnace, the arrangement beingpreferably so as. to cause the coal dust flame, whichv is generated inthe interior of the furnace in front of themouths of the nozzles, torush d )wn vertically onto thesmelting charge or bath resting on thehearth below. Owing to this particular arrangement, the highestgeneration of heat will take place in the middle of the furnace spaceabove the lowermost point ofthe smelting bath and, at the same time, thelargest part of the very intensive radiation heat will Vbe transmitteddirectly to the smelting charge without beingn first transferred to thefurnace wall/s. It is thereby rendered possible to melt materials ofhigh melting points and to make considerable savings 1n fuel at the sametime providing for a higher durability of the masonry of the furnace.

Another object of the invention is to improve with furnaces of thepresent kind the uniformity o'f the action of the heat on the severalpoints of the hearth, this being attained` by a novel construction ofthe re generators used fortpreheating the .secondary air as well as ofthe channels 1n com- 4 munication with the regenerators.

With these and other ends 1n view the invention consists in theconstruction, arrangement and combination of parts such as describedhereinafter and shown in lthe-'accompanying drawing, in which:

Fig. 1 is a view of the furnace and firing,

partly in longitudinal section and partly inv elevation; p

Fig. 2 is a horizontal section along the line II-II of Fig. 1;

Fig. 3 is a horizontal section along theA line III-III of Fig. 1; and

Fig. 4 isa vertical` section of the reversi ing device for controllingthe regenerator chambers.

The inner space of the furnace which is surrounded by the longitudinalwalls 1 and the end walls 2 which are shorter than the walls 1, iscovered in the -usual way by a crown 3 consisting of refractoryrbricks.` The bottom ofthe furnace space is rmed by the hearth 4 whichserves to receive the smelting charge' andthe surface of which islikewise lined with a layer of a suitable refracy tory material. v

The base of the furnace comprises four chambers 5, 6, 7, 8 which arecross-wise symmetrical and which contain the checker `work 9 of theregenerators consisting of refractory bricks. Each of the regeneratorchambers is in connection with the inner spaceA of the furnace by meansof a channel 10, 11,

.12 and 13, respectively, which extends vertically upwards near themiddle portion of the side walls 1 up to a point underneath the crown 3.f v

The channels 10, 11, 12, 13 open into the furnace space by taperingports 14 which are preferably inclined in a downward direction. lThereare, besides, provided four vertical channels 16, 17, 18 and 19, whichopen into the furnace space at 15 closelyl above the hearth and thelower ends of which are in communication with the regenerator chambers5, 6, 7 and 8. Below the checker works 9 the chambers 5, 6, 7, 8 areprovided each with a passage 20, 21, 22, 23 which are connectedcross-wise by two and two with channels 24 and 25, respectively,

`leading to the reversing valve 26 into which they open by two upwardldirected ports 28, 29.

Situated between t e two ports 28, s

29 is the mouth V30 of the flue 31 which is in constant communicationwith the chimi ney 32. 33 is a lbutterfly valve mounted for rotationaround a-horizontal axis above the `ports 28, 29, 30V and adapted toestablish communication between one of the ports 28 or 29 and the fluemouth 30 at the same time closing the .same with respect to the valvechamber 26 which is open to the atmosphere, while the other of the two,ports 28, 29 is placedinto communication with the atmosphere.

` i-The firing-of the 'furnace consists of a coal dust injecting nozzle34 which is mountlll ' to convey the coal dust through the piping is fedto the blower 37 from a bunker 40 through a vertical pipe 39. rllhequantity of the coal dust to be supplied in the unit of time iscontrolled by any of the wellknown measuring appliances which may be arotary valve or the like rotated by a sprocket wheel 4l at a speedcorresponding to the quantity of coal dust to be supplied.

'l rlhis sprocket wheel as well as another sprocket wheel 42, which isarranged at the lower end of the funnel-shaped outlet of the bunker 40and whichserves to operate a stirring mechanism arranged in the interiorof the bunker 40 and designed yto secure the uniformity of the coal dustsupply, are driven by a common sprocket chain 43 which is moved by asprocket wheel 44.-

Rotation is imparted to the latter by the driving shaft of the blower 37through the intermediary of a worm wheel 45 and a worm 46 as well as twopulleys 47, 48 and a driving belt 49. rlhe driving speed of the sprocketwheel 44 may be controlled by the intercalation of any suitable means.

During the working of the furnace, the combustion of the coal dustcurrent introduced into the furnace along with a certain quantity of airby the action of the blower 37 will take place in the middle of thefurnace space, while preheated secondary air flows in at the same timethrough two diagonally opposite ports 14 from the two respectiveregenerator chambers, whereby a complete combustion is secured. Owing tothe downwardly directed movement of the coal dust conveying air-currentand the downwardly inclined arrangement of the inlet ports 14, thecombustion gases will be blown onto the smelting charge resting on thehearth and thus directly transmit to the same a large part of theirheat, without the free development of the flame being in any wayimpeded. a

In the position vof the buttery valve 33 as shown in Fig. 4, the channel24 is in communication with the yiue 31. The two regenerator -chambers 5and 7 connected to the channel 24 are therefore subjected to the actionof the chimney draught, so that the combustion gases will be drawn olffrom the furnace space at diagonally opposite points through thechannels 16, 18 w ch are in communication with the said regeneratorchambers 5 and 7. At the Vsame time, the two other regenerator chambers6, 8 are 1n communication with the atmosphere through the connectingchannel 25 and its open outlet port 28. y In the kascending channels 11,13 which are in connection with those two chambers 6, 8, a strongascension is produced which will cause the heated air to flow intov thecombustion space of the furnace. rlfhe ascending action draws in freshair from the atmosphere through the channel 25, this air being heated inthe checker work of the two regenerator chambers 6, 8 and caused toenter the combustion space as preheated secondary air through thediagonally opposite outlet ports 14 as mentioned before. j

llf, after a certain time, the two regenerator chambers v6, 8 havecooled down to a certain degree, while the checker work of the two otherregenerator chambers 5, have been correspondingly heated by thecombustion gases which are passing to the chimney, the butterfly valve33 will be reversed so as to'place the channel 25 into communicationwith the flue 31 and the channel 24 into communication with theatmosphere. Fresh air will then flow through the twoA regeneratorehambers and 7, ascend in the channels 10 and 12 and enter thecombustion space by the Ipair of diagonally opposite ports 14 associatedwith such regenerators, while the combustion gases will pass from thecombustion space through the channels 17 and 19 down into the tworegeneratorchambers 6, 8, from which they flow through the channel 25'tothe Hue 31 and chimney 3.2.

It is to be understood that instead of one injecting nozzle 34, theremay be provided a plurality of such nozzles. In such case, the nozzlesare preferably arranged in a plurality of separate perforations of thecrown close beside one another near the middle of the furnace or.at moreor lesslarge distances in one or more longitudinal rows. rlhe nozzles'may then be directed to` the smelting charge at afmore or less largeinclination. Besides, the inlet ports for the preheated secondary' airmay be arranged in the furnace crown instead of in the side f walls.

Having thus described my invention, what l claim as new and desire tosecure by Letters-Patent, is :--l f. y

1. A smelting furnace including a smelting space having a perforation inthe crown thereof, a coal dust ring and a nozzle having its inletmounted in said perforation for injecting the powdered ing space. L

2. A smelting furnace comprising a coal dust ring,` a perforation in thecrownI of the furnace above the' hearth and a vertical y coal dustinjecting nozzle mounted in the said perforation.

3. A smelting furnace comprising a coal .l I I V:fuel into said smeltvlos dustfiring, means for injecting the coal dust into the combustionspace of the furnace, channels for supplying secondary air to thecombustion space and channels for leadinged the gases of combustion fromthe combustion space, the first-mentioned channels being 'arranged so asto open into the combustion space at the opposite longitudinalside-walls of the furnace and the secondly mentioned channels beingarranged so as to open into the combustion space at the oppositeend-walls of the furnace.

4. In a smelting furnace comprising a coal dust firing, a perforation inthe crown of the furnace, a vertical coal dust injecting nozzle in saidperforation, channels for supplying secondary air to the combustionspace of the furnace arranged so as to open into said space at theopposite side-walls of the furnace, and channels for leading-off thegases of combustion from the combustion space arranged -so as to openinto the same at the opposite end-walls of the furnace.

5. In a smelting furnace comprising a combustion space and a coal dustfiring, a perforation in the crown of the furnace, fuel injecting meansmounted in the said perforation, vfour regenerator chambers arrangedcrosswise underneath the combustion space, vertical channels arranged toconnect the combustion space 'at four diagonally opposite corners withthe regenerator chambers and adapted to lead-off the gases ofcombustion, and four other channels between the regenerator chambers andthe combustion space designed to supply the heated secondary air andarranged to open into the combustion space through the side-walls of thefurnace at points hlgher than the first mentioned channels.

6. In a smelting furnace comprising a combustion space and a coal dustfiring, a perforation in the crown of the furnace, fuel injecting meansmounted in the said perforation,^ four regenerator chambers arrangedcrosswise underneath the combustion space, a plurality of connectingchannels between the combustion space and the regenerator chambers, someof the channels being designed to supplythe secondary air and some ofthem being `designed to lead-off the gases of combustion, and channelsfor connecting the diagonally opposite regenerator chambers by two andtwo with` a re- ,Versing member adapted to connect these channelsalternately either with. the atmosphere or with the flue of the ehlmney.

signature.

\ In testimony, whereof I have aiiixed my`

